With reference to FIGS. 1 and 2, a fluid injector, generally indicated at 10, for use as a Reductant Delivery Unit (RDU) in a Selective Catalytic Reduction (SCR) system includes a primary O-ring 12 to seal urea being introduced into the injector 10 and to prevent liquid (e.g., water) ingress into the interior 16 of the injector 10. Even with the primary seal 12, as shown by the arrows in FIG. 2, water can ingress through the injector shield 14 and migrate below the primary O-ring 12 and enter the interior 16 of the injector 10 (between housing 26 and inlet tube 30). Such water ingress below the primary O-ring 12 can cause corrosion and or electrical short circuiting.
With reference to FIG. 3, Applicant added a secondary seal or O-ring 18 to eliminate water intrusion that may migrate below the primary O-ring 12. However, the secondary seal was found to prevent effective testing of the primary O-ring 12. Failure of the primary O-ring 12 would force AUS32 (urea, indicated by arrows in FIG. 3) into the interior 16 of the injector 10, leading to premature injector failure.
Accordingly, there exists a need in an injector a secondary seal to prevent ingress of liquid into the injector, while also allowing effective testing of the primary seal.